For larger scale brewing, drawdown should occupy 25-30% of the total contact time.
For single cup brewing, the necessity of keeping the slurry temperature sufficiently hot to promote good extraction yields needs to take precedence over the drawdown time profiling.
Spray heads with insufficient streams promote wells in the coffee bed.
01 sized flat-bed brewers promote even extraction but can trap grinds in the fluted edges.
Filter papers are fabricated with wet strength agents that create ionic bonds between the cellulose to make them stronger.